validate method
- String? value
override
Validates the value and returns an error string if it fails,
or null if it passes.
Implementation
@override
String? validate(String? value) {
if (value == null || value.isEmpty) return null;
if (value.length < minLength) return message;
if (requireUppercase && !RegExp(r'[A-Z]').hasMatch(value)) return message;
if (requireLowercase && !RegExp(r'[a-z]').hasMatch(value)) return message;
if (requireNumber && !RegExp(r'[0-9]').hasMatch(value)) return message;
if (requireSpecialChar && !RegExp(r'[^a-zA-Z0-9]').hasMatch(value)) {
return message;
}
return null;
}